This invention relates to a monitoring system for determining and indicating movement of an individual from one position to another. Several embodiments of the invention relate to determining and indicating when a patient is about to or is attempting to leave his bed. Another embodiment relates to determining and indicating when an individual merely raises his head from a recumbent position. Another embodiment relates to determining and indicates when a person, usually a child, is leaving a small area.
It is often desirable to know when an individual is attempting to crawl out of bed. This may occur, for example, in a hospital where the individual is an injured or ill adult or child; in a nursing home where the individual is an elderly or senile person; or in a nursery where the individual is a child. As used herein, the term patient is intended to encompass any individual who is supposed to remain in bed.
One of the common hospital accidents occurs when a patient climbs off of a hospital bed and is injured either by falling off the bed or by stumbling or falling after successfully getting out of bed. Because such accidents are, to a large extent, preventable, it is evident that there is a substantial interest in and need for a monitoring system to determine and indicate when a patient is in the process of getting out of bed without having to physically watch the patient at all times.
Essentially the same considerations are operative in nursing homes and other limited care facilities. In addition, there are numerous situations in a residence where it is desirable to know when an invalid, senile person or child is attempting to get out of bed.
It is accordingly not surprising that some effort has been expended in the development of devices to indicate when patients are getting out of bed or have gotten out of bed. For example, the disclosure in U.S. Pat. No. 3,852,736 utilizes a pressure or weight operative switch to sense the patient's weight. An alarm is energized when the switch is closed signifying an absence of patient weight. In this device, the weight sensitive switch is apparently basically a point sensor which indicates that the patient's weight is at a particular location which leads to false alarms when the patient merely rolls over in bed. False alarms have a particularly insidious effect because the attendant tends to disregard an alarm after the occurrence of one or more false alarms.
In U.S. Pat. No. 3,961,201, there is disclosed a pressure or weight sensitive switch located on the edge of a bed which trips an alarm upon the imposition of weight on the bed edge. Although this device is intended to detect when the patient is in the process of getting out of bed, the alarm can be falsely tripped merely by a visitor, for example, sitting on the edge of the bed. In U.S. Pat. No. 3,781,843, there is disclosed a device incorporating a pneumatic sensor in the guard rails of a hospital bed which trips an alarm when a weight is imposed on the guard rails. Although this device is likewise intended to indicate when a patient is in the process of climbing over the guard rails, false alarms are initiated merely by a visitor leaning on the guard rails.
It is also desirable, under certain circumstances, to know when a patient is moving from a recumbent position to a sitting position or when a patient is merely raising his head from a recumbent position, for example, when a patient has suffered a severe head injury and treatment dictates that the patient not raise his head.
It is also desirable, under certain circumstances, to know when an individual, typically a child, is moving out of a small area where the individual is known to be safe or where it is reasonable to expect that the individual will not over exert.
The present invention overcomes the foregoing and other disadvantages of the prior art by providing a novel and improved device for indicating when a patient is shifting weight on a bed from a normal recumbent or sitting position to another position indicative of egress from the bed.